Instrument for teaching coordination between written staff notes and corresponding musical tones

ABSTRACT

AN INSTRUMENT FOR TEACHING A PUPIL COORDINATION BETWEEN NOTES WRITTEN ON THE LINES AND SPACES OF A STAFF, AS IN SHEET MUSIC, AND THE ACTUAL CORRESPONDING MUSICAL TONES, HAS A HOUSING INCLUDING A PANEL FORMED WITH AN OPENING AND PREFERABLY HAVING A CLEF SIGN ADJACENT THE OPENING. A PLURALITY OF RELATIVELY ELONGATED SUBSTANTIALLY RECTANGULAR KEYS ARE ARRANGED IN THE OPENING AND INCLUDE ALTERNATING NARROW KEYS AND WIDE KEYS TO STIMULATE THE ALTERNATING LINES AND SPACES OF A MUSICAL STAFF. AN OSCILLATOR, A SOUND TRANSDUCER AND A BATTERY ARE MOUNTED IN THE HOUSING. A PRINTED CIRCUIT BOARD IS SUPPORTED WITHIN THE HOUSING ON A PAIR OF SPACED STRIPS OF RESILIENT MATERIAL, AND A SECOND PAIR OF SPACED STRIPS OF RESILIENT MATERIAL SUPPORT THE KEYS ON THE UPPER SURFACE OF THE PRINTED CIRCUIT BOARD. THE BATTERY HAS ONE TERMINAL GROUNDED TO THE HOUSING AND ITS OTHER TERMINAL ELECTRICAL CONNECTED TO THE PRINTED CIRCUITRY. A TAPPED RESISTANCE IS CONNECTED TO THE OSCILLATOR INPUT, AND IS ASSOCIATED WITH A CONDENSER TO PROVIDE AN R-C MEMBER. THE VALUE OF THE R-C MEMBER CONTROLS THE FREQUENCY OF THE OSCILLATOR. EACH KEY HAS AN ELECTRICALLY CONDUCTIVE STRIP ON ITS LOWER SURFACE WHICH, WHEN THE KEY IS DEPRESSED, CONNECTS A RESPECTIVE TAP OF THE RESISTANCE TO THE UNGROUNDED TERMINAL OF THE BATTERY. AS EACH KEY IS DEPRESSED, THE PRINTED CIRCUIT BOARD IS FIRST MOVED SLIGHTLY INWARDLY TO CONNECT PRINTED CIRCUITRY ON ITS UNDERSURFACE   TO METAL TABS FORMING PART OF THE METAL HOUSING. A PAIR OF RESISTANCES ARE INCLUDED IN SERIES WITH THE TAPPED RESISTANCE, AND ONE OF THIS PAIR OF RESISTANCES IS CONTROLLED BY A &#34;SHARP&#34; KEY OR THE &#34;FLAT&#34; KEY IS OPERATED, THE EITHER THE &#34;SHARP&#34; KEY OR THE &#34;FLAT&#34; KEY IS OPERATED, THE OSCILLATOR FREQUENCY IS CHANGED BY A HALF-TONE.

Dec- 7, 1971 R. a. mNGwALL ETAL 3,625,105

INSTRUMENT FOR TEACHING COORDINATION BETWEEN WRITTEN STAFF NOTES AND CORHESPONDING MUSICAL TONES 3 Sheets-Sheet 1 Filed Oct. 9, 1969 ROBERT INVIIDLN'IURS INGW LL WILLIAM RElMANeI CARMIN C. RAVOS L'l f/ j lay 0221A/ A T701? NE YS INSTRUMENT FOR TEACHING COORDINATION BETWEEN WRITTEN STAFF NOTES AND CORHESPONDING MUSICAL TONES 3 Sheets-Sheet 3 Filed Oct. 9, 1969 NGC Q Nww a, a. amw h E; INV/Nms ROBERT B. DINGWALL WILL/AM a. REIeMNN By CARMuvo c. RA 05A A TTORNE YS Dec. 7, 1971 R, B, DlNGwALL EI'AL 3,625,105

INSTRUMENT FOR TEACHING COORDINATION BETWEEN WRITTEN STAFF NOTES AND CORHESPONDING MUSICAL TONES Filed OC'C. 9, 1969 3 Sheets-Sheet 5 FIG. 5

WILLIAM REIMA NN BY CARMINO C. R VOSA @,Zaf ifm United.I States Patent O 3,625,105 INSTRUMENT FOR TEACHING COORDINATION BETWEEN WRITTEN STAFF NOTES AND COR- RESPONDING MUSICAL TONES Robert B. Dingwall and William B. Reimann, Mahopac,

and Carmino C. Ravosa, Briarclilf Manor, N.Y., assignors to Stanbow Productions, Inc., Valhalla, N.Y. Filed Oct. 9, 1969, Ser. No. 865,133 Int. Cl. G0911 /04 U.S. Cl. 84-471 12 Claims ABSTRACT OF THE DISCLOSURE An instrument for teaching a pupil coordination between notes written on the lines and spaces of a staif, as in sheet music, and the actual corresponding musical tones, has a housing including a panel formed with an opening and preferably having a clef sign adjacent the opening. A plurality of relatively elongated substantially rectang-ular keys are arranged in the opening and include alternating narrow keys and wide keys to stimulate the alternating lines and spaces of a musical staff. An oscillator, a sound transducer and a battery are mounted in the housing. A printed circuit board is s-upported within the housing on a pair of spaced strips of resilient material, and a second pair of spaced strips of resilient material support the keys on the upper surface of the printed circuit board. The battery has one terminal grounded to the housing and its other terminal electrical connected to the printed circuitry. A tapped resistance is connected to the oscillator input, and is associated with a condenser to provide an R-C member. The value of the R-C member controls the frequency of the oscillator. Each key has an electrically conductive strip on its lower surface which, when the key is depressed, connects a respective tap of the resistance to the -ungrounded terminal of the battery. As each key lis depressed, the printed circuit board is first moved slightly inwardly to connect printed circuitry on its undersurface to metal tabs forming part of the metal housing. A pair of resistances are included in series with the tapped resistance, and one of this pair of resistances is controlled by a sharp key and the other by a hat key. When either the sharp key or the flat key is operated, the oscillator frequency is changed by a half-tone.

' BACKGROUND OF THE INVENTION Key-operated electronic musical instruments have been well-known for many years. One of the better known forms of such a key-opertaed electronic musical instrument is represented by electronic organs, both of the stationary type and a portable type. Such instruments usually include one or more oscillators which, responsive to operation of a respective key, control a sound transducer to produce a tone correspnoding to the respective key.

It has been proposed to provide such a key-operated electronic instrument for use as a teaching aid in teaching pupils to read music printed on staffs, as in sheet music. However, the various devices proposed for this purpose have not provided a direct coordination between the spaces and lines of a staif and the keys of the teaching instr-ument. While some of these proposals have involved printing of a stair on a panel of the instrument, the lines and bars of the staff are merely printed and are not movable, so that the pupil must press a button or the like in order to produce a tone of the staff. Additionally, in these known proposals, the electric potential source is usually selfcontained, comprising a battery, for example. Switch means are provided for connecting the battery into the circuit key, and there is always a hazard that such switch means may be inadvertently left turned on, thus greatly 3,625,105 Patented Dec. 7, 1971 ice shortening the life of the battery so that the instrument rapidly becomes dead SUMMARY OF THE INVENTION This invention relates to instruments for teaching a pupil the tones corresponding to written staff notes and, more particularly, to an improved teaching instrument of this type of which there is a direct coordination between the written staff note and the key board of the instrument with respect to the alternating lines and spaces of a staff.

In accordance with the invention, a case or housing includes a panel having a substantially rectangular opening and preferably having a clef sign imprinted adjacent the opening. A plurality of relatively elongated substantially rectangular bars, constituting keys, are arranged in the opening in substantially a plane parallel to the panel. These bars include relatively narrow bars and relatively wide bars, and the narrow and wide bars are arranged in lateral alternation to simulate the alternating lines and spaces, respectively, of a musical staff. Additionally vthe relatively wide bars, representing the spaces of the statt, may be formed of white or clear plastic composition material and the relatively narrow bars, simulating the lines of the staff, may be formed of a colored, preferably black, plastic composition material.

Along each of the two lateral or longer edges of the opening, the housing is formed with a downturned Harige formed with downwardly opening slots receiving alternate keys. At spaced points along its length, each downturned flange is extended inwardly and then upwardly to form an upwardly opening channel. Each channel has placed therein a block of resilient materials such as, for example, a sponge rubber block. These blocks support a printed circuit board, having printed circuitry on both its upper surface and its lower surface.

The upper surface of the printed circuit board carries a rectangular frame, which may be secured thereto, and which abuts against the undersurface of the panel, the frame having a height such that, when it is abutted against the undersurface of the panel` the printed circuitry on the undersurface of the printed circuit board is spaced somewhat from the upturned ends of the extensions of the flanges. The printed circuit board is biased upwardly by the resilient blocks in the channels. When the circuit board is moved down a slight distance, the printed circuitrv on the surface is brought into contact with the iianges of the channels. The frame includes two opposite walls, one immediately at each shorter end of the panel opening and the other two being spaced somewhat outwardly from and extending substantially parallel to the flanges. These latter two walls of the frame are spaced apart a distance substantially equal to the length of the keys and thus act as retainers for the keys. The two shorter frame endwalls also act to maintain the alternating keys closely adjacent each other laterally.

The printed circuitry on the upper surface of the printed circuit board includes individual and isolated conductive strips, each longitudinally aligned with a respective key and each having a length nearly equal to the length of the associated key. Extending over these conductive metal strips, and substantially parallel to the longer sides of the panel opening, there are two laterally spaced blockshaped strips of resilient dielectric material such as sponge rubber. These strips bias the keys, relative to the printed circuit board, upwardly into an engagement with the closed upper ends of the slots or notches in the downturned flanges of the frame or housing. Each of the two resilient strips has extending along the entire length of its upper surface a respective electrically conductive metal strip, these two strips being interconnected to each other so as to form. in effect, a pair of parallel circuit wires.

On the underside of each key, there extends a respective wire spring or switch closer, each of which has down turned ends extending through apertures in the printed circuit 'board for retention of the spring. Outwardly of each resilient strip, each spring has a respective V-bend therein, the apex of which is normally spaced from the associated printed strip on the upper surface of the printed circuit board. When a key is depressed, either one or both V-bends of the associated spring will engage the associated printed strip and thus electrically connect the associated strip to the two metal strips extending along the upper surfaces of the foam rubber strips.

More importantly, as each key is depressed, it additionally causes the printed circuit board to move downwardly to bring the printed circuitry on its undersurface into contact with the flanges of the channels, thus connecting the circuitry on the undersurface of the printed circuit board to the metal panel of the metal housing. Further pressure on the key interconnects the strips as mentioned. The result is that the device is energized and a tone is produced corresponding to the particular key depressed.

The housing encloses a loudspeaker or the like, mounted adjacent sound emitting openings in the housing, and also has a bracket for interchangeably receiving a battery, such as a dry cell, having one terminal connected to the housing and thus grounded. The other terminal of the battery is electrically connected =to the two metal strips extending along the sponge rubber strips. A transistorized oscillator has its components mounted on the printed circuit board, and these components include a tapped resistance which determines the frequency of the oscillator. This tapped resistance includes individual resistances each connected between a pair of printed circuit strips on the upper surface of the printed circuit board. One end of the tapped resistance is connected to a pair of series connected individual resistances, one of which may be shorted by a normally open switch and the other of which is shorted by a normally closed switch. The other end-of these two individual resistances is connected to the oscillator input through an adjustable resistance. The normally open switch constitutes a sharp switch and the normally closed switch constitutes a flat switch.

Thus, Iby pressing on a particular one of the keys, such as a space or a 1ine, the amount of resistance incl-uded in the oscillator input, and associated with a charging condenser in the oscillator input, is such as to cause the oscillator to oscillate at a frequency corresponding to the tone of the particular key depressed. If the sharp switch is closed, the frequency is increased by a 'half tone and, if the flat switch is opened, the frequency is decreased by a half tone. These two switches likewise cooperate with the circuitry on the printed circuit board.

An object of the invention is to provide an improved teaching instrument for teaching a pupil coordination between written notes of a stati and the corresponding musical tones.

Another object of lthe invention is to provide such a teaching instrument including alternately arranged relatively wide and relatively narrow keys Simulating, respectively, the spaces and lines of a musical staff.

A further object of the invention is to provide such a teaching instrument in which, upon depression of a particular staff key, the corresponding tone is produced.

Another object of the invention is -to provide such teaching instrument in which there is a direct coordination between the writ-ten or sheet music and the keyboard of the instrument.

A fur-ther object of the invention is to provide such a teaching instrument in which an oscillator is normally disconnected from a source of potential and is automatically connected thereto responsive to depression of a stati key.

A further object of the invention is to provide such a teaching instrument including selectively operable switches for increasing or decreasing the oscillator frequency by a half tone, to sharp a tone or to at a tone.

Another object of the invention is to provide such a teaching instrument which is simple and inexpensive in construction, and rugged in operation.

For an understanding of ithe principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF TH'E DRAWINGS In the drawings:

FIG. 1 is a top plain view, partly broken away, of a teaching instrument embodying the invention;

FIG. 2 is an end and an elevation view of the instrument, looking from the left of FIG. 1;

FIG. 3 is a transverse sectional view of the instrument, taken on the line 3-3 of FIG. l; j

FIG. 4 is a transverse sectional view of the instrument, taken on the line 4-4 of FIG. 1; and

FIG. 5 is a schematic wiring diagram illustrating the electrical and electronic circuitry of the instrument.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 1 through 4, the teaching instrument includes a generally rectangular housing 10 having a bottom wall 11 and a sidewall 12. Housing 10 may :be formed of any suitable material, such as metal or plastic. At several locations, particularly at the corners thereof, housing 10 is formed with threaded apertured lugs 13 set somewhat downwardly from the upper edge of the side wall 12. These lugs serve to mount a rectangular metal panel 20 having apertures receiving screws 16 which are threaded into lugs 13.

Adjacent its right hand end, as viewed in FIG. 1, panel 20 is formed with a rectangular opening 25 extending transversely thereof. Along the two longer edges of opening 25, flanges 21 are bent downwardly perpendicular to the plane of panel 20, and anges 21 are formed with downwardly opening spaced slots 22. At spaced locations therealong, each flange 21 is formed with extensions 23 which extend inwardly and then upwardly to define lips 24, thus forming channels '26. The purpose of channels 26 will be made clear hereinafter.

In its left hand portion, `as viewed in FIG. 1, panel 20 is cut away and formed with an inwardly bent curved clip 27 to receive a dry cell or the like and, at the ends of the diameter of clip 27, tabs 28 are bent downwardly to cooperate with the ends of a battery inserted in clip 27. One tab 28 directly engages the center terminal of a battery 1S inserted into clip 27. The other tab 218 is apertured to receive an insulating bushing 17 in which is inserted a terminal 1'8 engaging the other end of battery 15. The left hand portion of panel 20 also serves to mount a speaker 30 and, adjacent to said speaker 30, panel 20 is formed with suitable sound outlet apertures 31.

In a manner to be described, the channels 26 serve to support a printed circuit board 35 which has printed circuitry 33 on its upper surface and printed circuitry 34 on its lower surface. The printed circuitry 33 on the upper surface of board 35 comprises a plurality of relatively narrow strips extending transversely of board 35 in spaced parallel relation therealong and each centrally aligned with a respective operating key of the instrument.

The printed circuitry 34 on the lower surface of board 35 comprises interconnected strips each extending longitudinally of board 35 and each aligned with the lips 24 on a respective iiange 21, the str-ips preferably being widened adjacent the upper ends of lips 24. These strips on the lower surface of board 35 are electrically connected to additional printed circuitry, for a purpose to be described hereinafter.

Printed circuit board 35 is formed with a plurality of preferably circular apertures therethrough each laligned with a respective extension 23 so that board 35 may be slipped up over these extensions, before the extensions are bent to form lips 24, to the position shown in FIG. 3. Board 35 is then supported on blocks 37 of suitable resilient material, such as, for example, sponge or Ifoam synthetic or natural rubber, seated in channels 26. The upper surface of board '35 lhas a rectangular frame 38 mounted or secured thereon, Iand the walls of frame 38 have a height such that, when blocks 37 urge or bias printed circuit board 35 toward panel 20, frame 38 will engage the panel in a position limiting upward movement of printed circuit board 35 to a position in which the mentioned printed circuitry strips on the lower surface thereof are spaced slightly above the up per ends of lips 24.

The operating keys 40 are res-iliently supported on the upper surface of circuit board 35, these keys comprising relatively wide keys 40A alternating with relatively narrow keys 401B. The wide keys 40A represent the spaces of a staff and the narrow keys 40B represents the lines of a staff.

To support keys 40, a pair of spaced parallel strips 41 of resilient material, such as synthetic or natural sponge or foam rubber or plastic, extend along the upper surface of printed circuit board 35, overlying the printed circuitry 33 thereon. The keys 40B extend through the slots 22 in flanges 21 of frame 20, and have twice the thickness of keys 40A. Keys extend beneath anges 21, whose depth is of the order of the thickness of narrow keys 40B. The ends of all the keys 40 substantially abut the longer edges of frame 38. Respective wire springs overlie cushion strips 41, beneath keys 40, each wire spring 45 being centrally aligned with a respective key 40. Springs 45 have downturned ends 46 which are engaged through apertures 42 in printed circuit board 35 to properly position the springs. Between each flange 21 and the adjacent cushion strip 41, each spring 45 is formed with a V-offset 47 whose apex, in the position of the keys 40 as shown in FIG. 3, is spaced slightly above the associated circuit strip forming part of the circuitry 33. Additionally, the springs 45 overlie conductive metal strips 43 each extending along the upper surface of a respective cushion strip 41, the strips 43 being electrically interconnected to each other.

With the arrangement thus far described, when a key 40 is depressed at any point along its length, printed circuit board 35 is moved downwardly to engage the longitudinal strips of printed circuitry 34 with one or more lips 24, thus connecting printed circuitry 34 to metal panel 20. Further downward movement engages one or both offsets 47 of the associated spring with the printed circuitry 33, thus interconnecting metal strips 43 and the respective circuitry strips 33. This not only effects connection of the circuitry of the instrument to both terminals of battery or cell but also, in a manner to be described, connects a particular magnitude of impedance, such as a tapped resistance, into the frequency controlling portion of the oscillator. The oscillator thereupon produces a tone having a frequency corresponding to that of the depressed key 40A or 40B.

The produced tone may be sharped or flatted, by a half tone in either case, by a sharp key 50A or a llat key 501B, these keys being located to the left of the keyboard represented by the space and line keys 40A and 40B, respectively.

Referring to FIG. 3, sharp key 50A comprises a button of dielectric material extending through an aperture in panel and formed with a downwardly opening recess receiving a bight 52 of a respective wire spring 55A, one leg 53 of bight 52 extending through a positioning slot in printed circuit board 35. The other leg of bight 52 is bent to extend substantially horizontally to overlie a resilient cushion strips 54 of natural or synthetic spong or foam rubber or plastic material positioned on the upper surface of printed circ-uit board 35.- Beyond strip 54 this leg is bent vertically downwardly to extend through an aperture 56 and then bent laterally to form an inverted V otset 57 which normally engages a printed circuit strip 48 on the undersurface of printed circuit board 35. To the left of cushion strip 54, spring 55A is formed with a downwardly directed V-otfset 58 which is normally spaced slightly above a printed circuit strip 44 on the upper surface of printed circuit board 35.

Referring to FIG. 4, fiat key 50B comprises a dielectric button extending through an aperture in panel 20 and formed with a downwardly opening recess 61 receiving a bight 62 of a wire spring 55B. One leg 63 of bight 62 extends downwardly through a slot at the end of printed circuit board 35 and it is then bent laterally and upwardly to 'form an inverted V-otset 64 normally engaged with printed circuit strip- 69. The other leg of bight l62 is bent laterally to extend across cushion strip 54 and is then bent downwardly to extend through an aperture 66 in printed circuit board 35, after which this leg is bent laterally and formed 'with an upwardly extending inverted V-offset 67 engage with a printed circuit strip 68. It will be noted that sharp switch 50A is a normally open switch and flat switch 50B is a normally closed switch.

Referring now to FIG. 5, which is a schematic wiring diagram of the circuitry of the instrument, the oscillator includes an NPN transistor T1 having a grounded emitter, a base connected to a junction point `65 and a collector connected to the base of a PNP transistor T2 Whose emitter is connected to the positive terminal of battery or cell 15. Transistor T2 lhas it-s collector connected to a junction point 70. The driving coil or winding 29 of speaker 30 is connected between junction point 70 and the ground. A condenser C1 is connected, in series with the resistor R2, to junction point 70, and a condenser CZ is connected in parallel with a resistor R1 across driving winding 29. A resistor R3 is connected between junction point 65 and ground, to serve as a stabilization resistance. An adjustable resistance R4 is connected between circuit strip 69 and junction point 65, and serves to adjust the range of the oscillator for component tolerance variation. A resistance R5 is connected vbetween circuit strips 68 and 69 and a resistance R6 is connected between circuit strips 44 and 48, strips 44 and-68 being electrically connected. It will be noted that resistance R5 is normally shunted by at switch 50B, and resistance R6 can be shunted by closing sharp r. s'witch 50A.

The frequency of the oscillator is determined by the magnitude of a frequency controlling impedance connected in the oscillator circuit. In the illustrated example, this impedance comprises a tapped resistance including a plurality of resistances `60 each connected between a pair o'f adjacent printed circuit strips 33. The conductive metal strips 43 are commonly connected to the positive terminal of battery or cell 15. Depending upon which of the keys 40A and 40B is depressed or operated, a respective wire spring switch 45 is closedto connect metal strips 43 to the respective printed circuit strip 33, and this determines the magnitude of resistance included in the oscillator circuit. Correspondingly, this controls the output frequency of the oscillator effective to drive the speaker 30I through winding 2'9.

When a key 40A 0r 40B is depressed, switch S1 is closed by engagement of printed circuitry 34 with the Ilips 24 of panel 20. Immediately thereafter, the wire spring switch 45 corresponding to the operated key connects one or both metal strips 43 to their associated printed circuit strip 33 to connect a predetermined magnitude of the tapped resistance in the oscillator circuit. Condenser or capacitor C1 charges through that magnitude of the tapped resistance then in circuit until there is sufficient potential at junction point -65 to cause transistor T1 to start conducting. When transistor T1 conducts, it causes transistor T2 to start conducting. The conduction of transistor T2 causes the potential at junction point 70 to increase, and this is seen, at the base of transistor T1, as an increase in base current so that 7 transistor T1 increases in conductivity causing transistor T2 to increase in conductivity. The current flowing through transistor T2 also passes through the exciting winding 29 of speaker 30 to produce the desired audible output from the speaker.

The base current for transistor T1 is being supplied by condenser or capacitor C1. When condenser C1 discharges to a point where transistor T1 can no longer maintain full conduction, the current flow from transistor T1 starts to decrease, and this is seen as a reduction in the base current of transistor T2. The reduction in base current of transistor T2 causes this transistor to decrease its conductivity so that the potential at junction point 70 moves in. a negative direction. This change is seen, at junction point 65, as a further reduction in base current lfor transistor T1. This multiplying effect shuts off transistors T1 and T2 so that current ceases to flow through 'winding 29. Condenser C1 then begins to charge at the selected R-C time and the cycle will continue to repeat until tht depressed key 40B is released. Thus, an output tone corresponding to the proper tone for the depressed key 40A or 40B is produced by speaker 30.

To sharp the tone, the sharp switch A is operated to shunt resistance R6, thus increasing the output tone by a half tone. Similarly, to flat the output tone, the flat switch 50B is operated to remove the shunt from resistance R5, thus 4decreasing the output tone by a half tone.

As best seen in FIGS. 1 and 3, a decorative cover plate 71 overlies the right hand portion of panel 20 and has a rectangular aperture 71a coextensively with aperture 25. Plate 71 is imprinted with extensions 72 and 73 of the lkeys 40A and 40B, respectively, and with a treble clef signature 74. Alternatively, a base clef signature could be used. The left half of panel is covered by a grill 75 having apertures 76, grill 75 slightly overlapping cover plate 71.

It will thus be seen that a simple and inexpensive teaching instrument is provided whereby a pupil, looking at a written note on a staff, can touch the staff represented by the keys 40A and 40B and thus hear the tone correspending to the particular written note. If the written note is a sharp note or a flat note, in addition to depressing the proper key 40A or 40B, the pupill can press either switch 50A or 50B to obtain a sharp note or a flat note. There is thus a direct coordination between the written music and the keyboard of the instrument, and the pupil does not have to look to find a marked button or the like. He merely looks at the scale, sees where the note is written, and then presses the corresponding space 40A or line 40B of the scale of the instrument. The instrument will operate regardless of where a key 40A or 40B is pressed, along its length.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A tea-ching instrument, for teaching a pupil coordination between notes, written or printed, on the lines and spaces of a staff, as in sheet music, and the actual musical tone of the respective notes, comprising, in combination, a housing including a panel having an opening: means in said opening defining a plurality of relatively elongated substantially rectangular independently operable keys, each having a planar uninterrupted outer Isurface, arranged in substantially a plan parallel to said panel and including first relatively narrow keys and second relatively wide keys, the first and second keys being arranged in lateral alternation to simulate the alternating lines and spaces, respectively, of a musical staff, and said keys being separate from each other over at least the major portion of their length; plural switch means each 8 operable by depression of only one respective key; an oscillator having an input circuit and an output circuit; a sound transducer connected in the output of the circuit of said oscillator; a source of potential and an impedance controlling the oscillator frequency in accordance with the magnitude of said impedance inserted between such source and said input circuit; each switch means, when operated by depression of the associated key, inserting, between said source and said input circuit, a respective magnitude of said impedance effective to cause said oscillator to oscillate at the frequency of the scale tone corresponding to its associated key.

2. A teaching instrument, as claimed in claim 1, in which said oscillator is normally effectively disconnected from said source of potentials; and further switch means, operable upon depression of any one of said rst and sectlnnd keys, to effect connection of said source to said oscilator.

3. A teaching instrument, as claimed in claim 1, including sharp means effective, when operated, to adjust the magnitude of said impedance to increase the frequency of said oscillator by one-half scale tone; and a flat means effective, when operated, to adjust the magnitude of said impedance to decrease the frequency of said oscillator by one-half a scale tone.

4. A teaching instrument, as claimed in claim 1, in which said impedance comprises a tapped resistance having a terminal connected to said oscillator input circuit; each switch means, when operated by depression of its associated key, connecting a respective tap of said impedance to a terminal of said source.

S. A teaching instrument, as claimed in claim 1, including rst and second resistances connected in series with each other between said terminal of said tapped resistance and the input circuit of said oscillator; a normally open sharp switch connected in shunt with said first resistance and effective, when closed, to said first resistance to adjust the magnitude of said impedance to increase the frequency of said oscillator by one-half a scale tone; and a normally closed flat switch connected in shunt with said second resistance and effective, when operated, to connect said second resistance in series with said tapped resistance to decrease the frequency of said oscillator by one-half of a scale tone.

6. A teaching instrument, as claimed in claim 1, in which said first relatively narrow keys, simulating the staff lines, are thicker than said second relatively wide keys, simulating the staff spaces, so as to project outwardly of said second keys.

7. A teaching instrument, for teaching a pupil coordination between notes, written or printed, on the lines and spaces of a staff, as in sheet music, and the actual musical tone of the respective notes, comprising, in combination, a housing including a panel having an opening;

a plurality of relatively elongated substantially rectangular keys arranged in said opening in substantially a plane parallel to said panel and including first relatively narrow keys and seconds relatively wide keys, the first and second keys being arranged in lateral alternation to simulate the alternating lines and spaces, respectively, of a musical staff; plural switch means each operable by depression of the respective key; an oscillator having an input circuit and an Output circuit; a sound transducer connected in the output of the circuit of said oscillator; a source of potential; an impedance controlling the oscillator frequency in accordance with the magnitude of said impedance inserted between such source and said input circuit; each switch means, when operated by depression of the associated key, inserting, between said source and said input circuit, a respective magnitude of said impedance effective to cause said oscillator to oscillate at the frequency of the scale tone corresponding to its associated key; said oscillator being normally effectively disconnected from said source of potentials; further switch means, operable upon depression of any one of said first and second keys, to effect connection of said source to said oscillator; a printed circuit board positioned beneath and in spaced relation to said panel and extending across said opening; first resilient means supporting said printed circuit board and -biasing the latter toward said panel; means limiting movement of said circuit board towards the panel; and second resilient means on the upper surface of said printed circuit board supporting said rst and second keys; said further switch means including printed circuitry on the undersurface of said printed circuit board and associated Contact means normally spaced from said printed circuit means; each of said first and second keys, when depressed, initially moving said printed circuit board away from said panel to engage said printed circuit means with said contact means to connect said oscillator to said source, and thereafter closing the associated lirst-mentioned switch means.

8. A teaching instrument, as claimed in claim 7, in which the upper surface of said printed circuit board has printed thereon conductive strips extending in spaced parallel relation to each other and centered beneath one of said first and second keys; said second resilient means comprising plural elongated strips of resilient dielectric material extending transversely of said conductive strips; respective strips of electrically conductive metal each extending longitudinally of one of said strips of resilient dielectric material and commonly connected to one terminal of said source; said first-mentioned switch means comprising a plurality of wire springs each operatively associated with a respective one of said rst and second keys and interposed between the respective key and said conductive metal strips, said Wire springs extending'longitudinally of the associated lirst and second keys and having ends guided in said printed circuit board; each Wire spring having bent portions extending downwardly therefrom and normally spaced slightly from the associated l0 conductive strip; said wire springs and said conductive strips constituting said first-mentioned spring means.

9. A teaching instrument, as claimed in claim 8, in which said impedance means comprises plural resistances each electrically connected between a pair of said conductive strips, whereby each conductive strip forms a tap of a tapped resistance; one terminal of said tapped resistance being connected to the input circuit of said oscillator.

10. A teaching instrument, as claimed in claim 9, including a pair of resistances connected in series with each other to said input circuit; a normally open sharp key switch in shunt with one of said pair of resistances and a normally closed flat key switch connected in shunt with the other of said pair of resistances.

1l. A teaching instrument, as claimed in claim 10, including an adjustable resistance connected in series between said pair of resistance and said input circuit and effective to adjust the range of said instrument for components tolerance variations.

12. A teaching instrument, as claimed in claim 10, including a capacitor included in said oscillator and constituting, with said tapped resistance, a R-C member controlling the frequency of said oscillator.

References Cited UNITED STATES PATENTS 2,888,849 6/1'959 Humphrey et al 84-470 3,429,216 2/ 1969 Lawrence 84-471 3,460,425 8/1969 Kiepe 84-470 3,512,445 5/1970 Aaron 84-471 3,520,983 7 1970 DAgata 84-470 RICHARD B. WILKINSON, Primary Examiner L. R. FRANKLIN, Assistant Examiner 

